(GLn, GLm)-duality and symmetric plethysm
In  the author has given an exposition of the theory of invariants of binary forms in terms of a particular version of Classical Invariant Theory. Reflection shows that many aspects of the development apply also ton-ary forms. The purpose of this paper is to make explicit this more general application. The plethysms S’(Sp(ℂn)) are computed quite explicitly forl = 2, 3 and 4.
Roger Howe1 2